In case you are using seek= as well, you may also consider oflag=seek_bytes.

From info dd:

count_bytes: Interpret the count= operand as a byte count, rather than a block count, which allows specifying a length that is not a multiple of the I/O block size. This flag can be used only with iflag.

skip_bytes: Interpret the skip= operand as a byte count, rather than a block count, which allows specifying an offset that is not a multiple of the I/O block size. This flag can be used only with iflag.

seek_bytes: Interpret the seek= operand as a byte count, rather than a block count, which allows specifying an offset that is not a multiple of the I/O block size. This flag can be used only with oflag.